1. Field of the Invention
This invention generally relates to copy protection of CDROM media. More specifically, the invention addresses the problem of the illegal copying and distribution (or xe2x80x9cpiratingxe2x80x9d) of copyrighted digital information written on CD type storage media. This proprietary information may include a variety of software programs such as operating system software, application programs, and entertainment games.
2. Prior Art
The preferred method of commercially distributing software packages in today""s information age is to use a relatively inexpensive and simple to read CDROM media. Data are recorded in a CDROM along a substantially spiral line beginning at an interior radius and continuing out to larger radii. Data is recorded on the disk in the form of bit indications consisting of lands and pits alternating along the centerline, the arcuate length of each land or pit indicating the number of sequential xe2x80x9czeroxe2x80x9d bits in the data. The data to be recorded on the disk are converted from binary to a format known as eight-to fourteen modulation (EFM). The EFM data is written at a constant linear velocity (CLV) along the spiral, such that the xe2x80x9c1xe2x80x9d in the EFM data produces a transition from land to pit or vice versa, and each xe2x80x9c0xe2x80x9d in the EFM data produces no transition.
Until recently this approach was relatively secure from xe2x80x9cpiratingxe2x80x9d since the equipment to write CDROMs was technically complex, quite expensive, and not readily available. In the last couple of years, however, advances in CD technology have developed writeable CDROM equipment that is readily available and inexpensive.
These writeable CDROM drives, supporting software, and blank CDROMs can be purchased for a few hundred dollars and easily installed on most personal computers.
The capability to use CDROMs for general user storage applications, both read-only and write-once, is of great benefit to the individual personal computer user and the computer industry as a whole. This analog and digital storage technology provides a reliable and inexpensive high capacity storage media for a wide range of digital and analog applications, but at the same time, this technology is susceptible to illegal reproduction of proprietary data. Unless a reliable copy protection method is developed, these benefits may not be fully achieved.
One current solution to this problem is to provide indirect protection by associating a control number with the CDROM media that is requested while installing the software package. This control number is provided with the original CDROM, but can be easily copied and distributed with the illegally copied CDROM.
Another solution is to provide specific or temporary licensing for the application software. This approach requires additional ongoing support, is inconvenient, more restrictive, and more expensive to distribute. Although this approach can achieve copy protection of extensive software packages for large systems, it is not applicable to individual or personal computing software distribution.
An object of this invention is to protect copyrighted digital information on CD type storage media.
Another object of the present invention is to provide a method and system for protecting copyrighted digital information on CD type storage media that are easy to implement, are compatible with CDROM mass production, and provide almost foolproof copy protection.
A further object of this invention is to protect copyrighted digital information on CD type storage media in a way that does not require any additional distribution costs, is applicable to a wide variety of application software packages, and is extensible to digitized audio and video media.
Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description, given with reference to the accompanying drawings, which specify and show preferred embodiments of the invention.
These and other objectives are attained with a method of forming an optical disc, and an optical disc formed, so as to facilitate identifying unauthorized copies of the disc by using a defined procedure for reading the disc. The method comprises the steps of encoding digital data, comprised of a series of 0s and 1s, in the disc by forming a series of spaced pits along a track, so that the track comprises a series of pits and lands, and wherein, when said defined procedure is used to read the disc, each of said pits and lands is read as either a 0 or a 1. The method comprises the further step of forming at least one fuzzy area on the track so that when the defined procedure is used to read the disc, the fuzzy area is sometimes read as 0 and sometimes read as 1. With a preferred procedure, the pits reflect a given light beam at a first intensity, the lands reflect the given light at a second intensity, and the fuzzy area reflects the given light at a third intensity substantially midway between the first and second intensities.